The beetles play a key role in the ecosystem functioning and they are also important for monitoring impacts of environmental changes. Even studied intensively, the identification of beetle species often remains problematic. However, development of robust DNA barcode database could help overcome this problem. The main source of DNA barcodes is the project Barcode of Life, including ca. 4,5 million of sequences. There are 464 sequences of ca 30 Elmidae species, small fraction of about 1500 known species. The goal of this project is taxonomic analysis of uniquely rich material of Elmidae, producing and analysis of new DNA barcodes (min 1000 new sequences), thorough comparisons of taxonomic results gained using morphological and molecular characters (estimating applicability of DNA barcodes for elmid taxonomy), new taxa description, phylogeny of taxa studied, evaluation of relationships between species and genetic diversity and evaluation of Elmidae DNA barcode data applicability in monitoring and conservation.